/*******************************************************************************
 * Copyright (c) 2009, 2019 Xored Software Inc and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-v20.html
 *
 * Contributors:
 *     Xored Software Inc - initial API and implementation and/or initial documentation
 *******************************************************************************/
package org.eclipse.rcptt.ecl.data.internal.commands;

import java.util.Vector;
import java.util.regex.Pattern;

import org.eclipse.rcptt.ecl.data.commands.RowMatchMode;

public class TableRowMatcher {
	public interface IMatcher {
		boolean match(String value);
	}

	private static class Position {
		int start; // inclusive
		int end; // exclusive

		public Position(int start, int end) {
			this.start = start;
			this.end = end;
		}

		@SuppressWarnings("unused")
		public int getStart() {
			return start;
		}

		@SuppressWarnings("unused")
		public int getEnd() {
			return end;
		}
	}

	/**
	 * A string pattern matcher. Supports '*' and '?' wildcards.
	 */
	public class StringMatcher {
		protected String fPattern;
		protected int fLength; // pattern length
		protected boolean fIgnoreWildCards;
		protected boolean fIgnoreCase;
		protected boolean fHasLeadingStar;
		protected boolean fHasTrailingStar;
		protected String fSegments[]; // the given pattern is split into *
										// separated segments

		/* boundary value beyond which we don't need to search in the text */
		protected int fBound = 0;

		protected static final char fSingleWildCard = '\u0000';

		/**
		 * StringMatcher constructor takes in a String object that is a simple
		 * pattern. The pattern may contain '*' for 0 and many characters and
		 * '?' for exactly one character.
		 * 
		 * Literal '*' and '?' characters must be escaped in the pattern e.g.,
		 * "\*" means literal "*", etc.
		 * 
		 * Escaping any other character (including the escape character itself),
		 * just results in that character in the pattern. e.g., "\a" means "a"
		 * and "\\" means "\"
		 * 
		 * If invoking the StringMatcher with string literals in Java, don't
		 * forget escape characters are represented by "\\".
		 * 
		 * @param pattern
		 *            the pattern to match text against
		 * @param ignoreCase
		 *            if true, case is ignored
		 * @param ignoreWildCards
		 *            if true, wild cards and their escape sequences are ignored
		 *            (everything is taken literally).
		 */
		public StringMatcher(String pattern, boolean ignoreCase,
				boolean ignoreWildCards) {
			if (pattern == null)
				throw new IllegalArgumentException();
			fIgnoreCase = ignoreCase;
			fIgnoreWildCards = ignoreWildCards;
			fPattern = pattern;
			fLength = pattern.length();

			if (fIgnoreWildCards) {
				parseNoWildCards();
			} else {
				parseWildCards();
			}
		}

		/**
		 * Find the first occurrence of the pattern between <code>start</code
		 * )(inclusive) and <code>end</code>(exclusive).
		 * 
		 * @param text
		 *            the String object to search in
		 * @param start
		 *            the starting index of the search range, inclusive
		 * @param end
		 *            the ending index of the search range, exclusive
		 * @return an <code>StringMatcher.Position</code> object that keeps the
		 *         starting (inclusive) and ending positions (exclusive) of the
		 *         first occurrence of the pattern in the specified range of the
		 *         text; return null if not found or subtext is empty
		 *         (start==end). A pair of zeros is returned if pattern is empty
		 *         string Note that for pattern like "*abc*" with leading and
		 *         trailing stars, position of "abc" is returned. For a pattern
		 *         like"*??*" in text "abcdf", (1,3) is returned
		 */
		public Position find(String text, int start, int end) {
			if (text == null)
				throw new IllegalArgumentException();

			int tlen = text.length();
			if (start < 0)
				start = 0;
			if (end > tlen)
				end = tlen;
			if (end < 0 || start >= end)
				return null;
			if (fLength == 0)
				return new Position(start, start);
			if (fIgnoreWildCards) {
				int x = posIn(text, start, end);
				if (x < 0)
					return null;
				return new Position(x, x + fLength);
			}

			int segCount = fSegments.length;
			if (segCount == 0)// pattern contains only '*'(s)
				return new Position(start, end);

			int curPos = start;
			int matchStart = -1;
			int i;
			for (i = 0; i < segCount && curPos < end; ++i) {
				String current = fSegments[i];
				int nextMatch = regExpPosIn(text, curPos, end, current);
				if (nextMatch < 0)
					return null;
				if (i == 0)
					matchStart = nextMatch;
				curPos = nextMatch + current.length();
			}
			if (i < segCount)
				return null;
			return new Position(matchStart, curPos);
		}

		/**
		 * match the given <code>text</code> with the pattern
		 * 
		 * @return true if matched eitherwise false
		 * @param text
		 *            a String object
		 */
		public boolean match(String text) {
			return match(text, 0, text.length());
		}

		/**
		 * Given the starting (inclusive) and the ending (exclusive) positions
		 * in the <code>text</code>, determine if the given substring matches
		 * with aPattern
		 * 
		 * @return true if the specified portion of the text matches the pattern
		 * @param text
		 *            a String object that contains the substring to match
		 * @param start
		 *            marks the starting position (inclusive) of the substring
		 * @param end
		 *            marks the ending index (exclusive) of the substring
		 */
		public boolean match(String text, int start, int end) {
			if (null == text)
				throw new IllegalArgumentException();

			if (start > end)
				return false;

			if (fIgnoreWildCards)
				return (end - start == fLength)
						&& fPattern.regionMatches(fIgnoreCase, 0, text, start,
								fLength);
			int segCount = fSegments.length;
			if (segCount == 0 && (fHasLeadingStar || fHasTrailingStar)) // pattern
																		// contains
																		// only
																		// '*'(s)
				return true;
			if (start == end)
				return fLength == 0;
			if (fLength == 0)
				return start == end;

			int tlen = text.length();
			if (start < 0)
				start = 0;
			if (end > tlen)
				end = tlen;

			int tCurPos = start;
			int bound = end - fBound;
			if (bound < 0)
				return false;
			int i = 0;
			String current = fSegments[i];
			int segLength = current.length();

			/* process first segment */
			if (!fHasLeadingStar) {
				if (!regExpRegionMatches(text, start, current, 0, segLength)) {
					return false;
				} else {
					++i;
					tCurPos = tCurPos + segLength;
				}
			}
			if ((fSegments.length == 1) && (!fHasLeadingStar)
					&& (!fHasTrailingStar)) {
				// only one segment to match, no wildcards specified
				return tCurPos == end;
			}
			/* process middle segments */
			while (i < segCount) {
				current = fSegments[i];
				int currentMatch;
				int k = current.indexOf(fSingleWildCard);
				if (k < 0) {
					currentMatch = textPosIn(text, tCurPos, end, current);
					if (currentMatch < 0)
						return false;
				} else {
					currentMatch = regExpPosIn(text, tCurPos, end, current);
					if (currentMatch < 0)
						return false;
				}
				tCurPos = currentMatch + current.length();
				i++;
			}

			/* process final segment */
			if (!fHasTrailingStar && tCurPos != end) {
				int clen = current.length();
				return regExpRegionMatches(text, end - clen, current, 0, clen);
			}
			return i == segCount;
		}

		/**
		 * This method parses the given pattern into segments seperated by
		 * wildcard '*' characters. Since wildcards are not being used in this
		 * case, the pattern consists of a single segment.
		 */
		private void parseNoWildCards() {
			fSegments = new String[1];
			fSegments[0] = fPattern;
			fBound = fLength;
		}

		/**
		 * Parses the given pattern into segments seperated by wildcard '*'
		 * characters.
		 */
		private void parseWildCards() {
			if (fPattern.startsWith("*"))//$NON-NLS-1$
				fHasLeadingStar = true;
			if (fPattern.endsWith("*")) {//$NON-NLS-1$
				/* make sure it's not an escaped wildcard */
				if (fLength > 1 && fPattern.charAt(fLength - 2) != '\\') {
					fHasTrailingStar = true;
				}
			}

			Vector<String> temp = new Vector<String>();

			int pos = 0;
			StringBuffer buf = new StringBuffer();
			while (pos < fLength) {
				char c = fPattern.charAt(pos++);
				switch (c) {
				case '\\':
					if (pos >= fLength) {
						buf.append(c);
					} else {
						char next = fPattern.charAt(pos++);
						/* if it's an escape sequence */
						if (next == '*' || next == '?' || next == '\\') {
							buf.append(next);
						} else {
							/* not an escape sequence, just insert literally */
							buf.append(c);
							buf.append(next);
						}
					}
					break;
				case '*':
					if (buf.length() > 0) {
						/* new segment */
						temp.addElement(buf.toString());
						fBound += buf.length();
						buf.setLength(0);
					}
					break;
				case '?':
					/*
					 * append special character representing single match
					 * wildcard
					 */
					buf.append(fSingleWildCard);
					break;
				default:
					buf.append(c);
				}
			}

			/* add last buffer to segment list */
			if (buf.length() > 0) {
				temp.addElement(buf.toString());
				fBound += buf.length();
			}

			fSegments = new String[temp.size()];
			temp.copyInto(fSegments);
		}

		/**
		 * @param text
		 *            a string which contains no wildcard
		 * @param start
		 *            the starting index in the text for search, inclusive
		 * @param end
		 *            the stopping point of search, exclusive
		 * @return the starting index in the text of the pattern , or -1 if not
		 *         found
		 */
		protected int posIn(String text, int start, int end) {// no wild card in
																// pattern
			int max = end - fLength;

			if (!fIgnoreCase) {
				int i = text.indexOf(fPattern, start);
				if (i == -1 || i > max)
					return -1;
				return i;
			}

			for (int i = start; i <= max; ++i) {
				if (text.regionMatches(true, i, fPattern, 0, fLength))
					return i;
			}

			return -1;
		}

		/**
		 * @param text
		 *            a simple regular expression that may only contain '?'(s)
		 * @param start
		 *            the starting index in the text for search, inclusive
		 * @param end
		 *            the stopping point of search, exclusive
		 * @param p
		 *            a simple regular expression that may contains '?'
		 * @return the starting index in the text of the pattern , or -1 if not
		 *         found
		 */
		protected int regExpPosIn(String text, int start, int end, String p) {
			int plen = p.length();

			int max = end - plen;
			for (int i = start; i <= max; ++i) {
				if (regExpRegionMatches(text, i, p, 0, plen))
					return i;
			}
			return -1;
		}

		protected boolean regExpRegionMatches(String text, int tStart,
				String p, int pStart, int plen) {
			while (plen-- > 0) {
				char tchar = text.charAt(tStart++);
				char pchar = p.charAt(pStart++);

				/* process wild cards */
				if (!fIgnoreWildCards) {
					/* skip single wild cards */
					if (pchar == fSingleWildCard) {
						continue;
					}
				}
				if (pchar == tchar)
					continue;
				if (fIgnoreCase) {
					if (Character.toUpperCase(tchar) == Character
							.toUpperCase(pchar))
						continue;
					// comparing after converting to upper case doesn't handle
					// all cases;
					// also compare after converting to lower case
					if (Character.toLowerCase(tchar) == Character
							.toLowerCase(pchar))
						continue;
				}
				return false;
			}
			return true;
		}

		/**
		 * @param text
		 *            the string to match
		 * @param start
		 *            the starting index in the text for search, inclusive
		 * @param end
		 *            the stopping point of search, exclusive
		 * @param p
		 *            a string that has no wildcard
		 * @return the starting index in the text of the pattern , or -1 if not
		 *         found
		 */
		protected int textPosIn(String text, int start, int end, String p) {

			int plen = p.length();
			int max = end - plen;

			if (!fIgnoreCase) {
				int i = text.indexOf(p, start);
				if (i == -1 || i > max)
					return -1;
				return i;
			}

			for (int i = start; i <= max; ++i) {
				if (text.regionMatches(true, i, p, 0, plen))
					return i;
			}

			return -1;
		}
	}

	public TableRowMatcher() {
		super();
	}

	protected IMatcher createMatcher(RowMatchMode match, final String pattern) {
		switch (match) {
		case GLOB:
			return new IMatcher() {
				StringMatcher sm = new StringMatcher(pattern, true, false);

				public boolean match(String value) {
					return sm.match(value);
				}
			};
		case REGEXP:
			return new IMatcher() {
				Pattern p = Pattern.compile(pattern);

				public boolean match(String value) {
					return p.matcher(value).find();
				}
			};
		default:
			return new IMatcher() {
				public boolean match(String value) {
					return pattern.equals(value);
				}
			};
		}
	}

}